The present invention relates to a method for isolating a fraction having anti-inflammatory or osteoarthritis-inhibiting effects using oyster shell. More particularly, the present invention relates to a method for isolating a fraction having anti-inflammatory or osteoarthritis-inhibiting effects which comprises removing foreign materials attached to the oyster shell, washing the oyster shell with water and then drying the washed oyster to make a powder, reacting the powder with anhydrous citric acid to obtain a reaction product, centrifuging the reaction product to obtain a supernatant and then subjecting to ultra-filtration. Since the reaction between oyster shell and anhydrous citric acid occurs at a relatively low temperature, the energy cost can be reduced and a fraction having anti-inflammatory or osteoarthritis-inhibiting effects can be isolated in a relatively simple way.
In Korea, about nine hundred thousand tons of oyster shells are produced a year, of which it is estimated that seven hundred thousand tons are discarded. The discarding of oyster shells has emerged as a serious pollution problem and has come under economic scrutiny. The main component of oyster shells is calcium carbonate (CaCO3) which comprises about 95% of the oyster shell. Magnesium carbonate (MgCO3) and calcium sulfate (CaSO4) are also present in small quantities. The oyster shell is used as a raw material in, for example, various fillers, paper coating agents, pigments, cosmetics and pharmaceuticals, and it is even used in the manufacture of calcium carbonate (CaCO3). In Japan, studies to utilize the oyster shell as a soft ground improving material and a sand pile material have been performed. In Korea, attempts to increase the recycling of oyster shells in calcium plants and fertilizer plants have been made, but an appropriate treatment plan has not yet been suggested.
On the other hand, inflammation in a living body or tissue is caused by a series of reactions which are induced by a number of stimulus such as infectious agents, ischemia, antigen-antibody reactions, heat, or physical injury. The inflammation reaction is known to display clinical symptoms such as erythema, edema, tenderness and pain. Arachidonic acid produces a variety of prostaglandins which play an important role in in vivo inflammation delivery by cyclo-oxygenase (COX), and a thromboxane involved in platelet aggregation. The COX enzyme is composed of COX-1 enzymes which plays an important role in maintaining homeostasis in normal tissues, and COX-2 enzymes, which are inducible enzymes whose expression is increased temporarily by inflammation. COX-1 enzymes are enzymes used in the production of a material (thromboxan A2) which coagulates blood, prevents blood circulation and constricts blood vessels, and are also enzymes used in the production of a mucous membrane-protecting material that functions to prevent destruction of the gastric mucous membrane.
On the other hand, COX-2 (type 2; induced form) enzymes are mainly found in the brain and kidney, and may also be found even in inflammatory cells. Particularly, COX-2 is known to be derived from the site of inflammation. COX-2 enzymes are enzymes used for generating Prostaglandin E2, a material that causes inflammation. They are also known as enzymes which promote production of Prostaglandin I2, a material that functions to prevent thrombosis and extend the blood vessel.
Inflammatory response is a mechanism for restoring and regenerating a site injured by invasiveness which gives rise to an organic lesion caused by a physical action or a chemical substance or a bacterial infection. Once the stimulus has been topically applied, substances active in blood vessels such as histamine, serotonine, bradykinin, prostaglandins, hydroxyl-eicosatetraenoic acid (HETE), and leuko-triene are isolated to induce inflammation while increasing vascular permeability. Moderate inflammation that occurs quickly following an injury is a normal reaction to quickly regenerate the injured site.
However, a long-term persistent inflammatory response may have difficulty in regenerating the injured site and can cause harm to the surrounding cells, thereby lowering a defensive power to the peripheral tissue and worsening the symptoms. Furthermore, a long-term persistent inflammatory response causes a sustained damage to the surrounding tissues. As a result, some types of inflammatory response may cause diseases such as cancer.
Thus, a tissue showing inflammation response would need to be treated with appropriate anti-inflammatory agents so that the regeneration process is completed in a short amount of time. However, topical steroids which are used to treat inflammatory diseases exhibit several side effects and so the use thereof is limited. The development of anti-inflammatory drugs having excellent efficacy and few side effects is urgently required (see Miller M. J. et al., Mediators of Inflammation, 4, pp 387-396. 1995: Appleton L. et al., Adv Pharmacol., 35, pp 27-28, 1996).
Further, recently, as Korea develops into an aging society, it has been shown that about 80% over 55 and all of those over 75 have osteoarthritis diseases. Especially, knee osteoarthritis is a disease having high societal costs such as treatment expenses as well as social activity impairment in an aging population, because the incidence is very high and sustained inflammations can induce peripheral muscle atrophy, thus causing abnormalities in the joints.
Osteoarthritis (degenerative arthritis) is a disease afflicting seniors which is frequently observed clinically, and the lesions thereof develop as a result of degeneration of the joint cartilage, and pain and swelling, joint stiffness and progressive movement disorders occur upon exercise. In osteoarthritis, inflammatory mediators such as cytokines are known to be involved in the degeneration of matrix components of joint cartilage tissue (see Pelletier et al, 1993). In particular, interleukin-1β (IL-1β) is widely accepted as one of the important pro-inflammatory cytokines which are involved in pathophysiology of the osteoarthritis (see Dinarello et al., 1988). This induces a sequential catabolism in chondro site including the up-regulation of COX gene and the release of prostaglandin E2 (see Stichtenoth et al, 2001).
Even though a non-steroidal anti-inflammatory drug during such pharmacological treatment has serious side effects, it is one of the most widely prescribed types of drugs for osteoarthritis for the long-term administration (see Abramson et al, 2003). However, recently, in order to develop strategies to prevent the onset and progress of osteoarthritis, new research and efforts have been steadily performed.